An accessory navicular bone is an accessory bone of the foot that occasionally develops abnormally in front of the ankle towards the inside of the foot. This bone may be present in approximately 2-14% of the general population and is usually asymptomatic. When it is symptomatic, surgery may be necessary. Surgery can be performed at any age because it does not alter any other bones.Causes
An injury to the fibrous tissue connecting the two bones can cause something similar to a fracture. The injury allows movement to occur between the navicular and the accessory bone and is thought to be the cause of pain. The fibrous tissue is prone to poor healing and may continue to cause pain. Because the posterior tibial tendon attaches to the accessory navicular, it constantly pulls on the bone, creating even more motion between the fragments with each step.Symptoms
Adolescence is a common time for the symptoms to first appear. This What is leg length discrepancy
? a time when bones are maturing and cartilage is developing into bone. Sometimes, however, the symptoms do not occur until adulthood. The signs and symptoms of accessory navicular syndrome include a visible bony prominence on the midfoot (the inner side of the foot, just above the arch) Redness and swelling of the bony prominence. Vague pain or throbbing in the midfoot and arch, usually occurring during or after periods of activity.Diagnosis
Typically, accessory navicular syndrome isn?t hard to diagnose. Our podiatrists will examine the lower limb and check the hard prominence, as well as use X-rays to confirm the presence of extra bone tissue. Other diagnostic images may be able to identify inflammation and specific damage to the midfoot. Depending on the severity of your discomfort, conservative measures may be enough to resolve the condition.Non Surgical Treatment
The foot may be placed in a cast or removable walking boot to allow the affected area to rest and decrease the inflammation. Physical therapy including exercises and treatments to strengthen the muscles, decrease inflammation, and prevent recurrence of the symptoms. Custom orthopedic devices that fit into the shoe providing arch support. Even after successful treatment, symptoms may reappear.Surgical Treatment
In the original Kidner procedure, the entire posterior tibial tendon was released from the navicular and then rerouted through a drill hole placed through the navicular. The original Kidner procedure is now rarely used as a means of treating an isolated accessory navicular. Instead, a modification of the Kidner procedure has become more commonplace. The modified Kidner procedure consists of carefully removing the accessory and anchoring the posterior tibial tendon to the surface of the navicular where the accessory was removed. The repair may be done by passing a suture through the tendon and then through drill holes in the navicular, or by using a suture anchor.